[Pete]

JWL covered it.
I have tested and used the Neoprene or Viton tipped needles and they will also work fine at 7 or 8 lb. I have always run 6 lb on my Strombergs. With any needle setup, the bowls will run dry at 6000 rpm on the straight of a half mile circle track.
The original steel needles will work forever on the street as long as you keep the dirt out.